Influence of secretin and caerulein on acid phosphatase activity in human saliva

Experimental studies have demonstrated a structural and functional correlation between the pancreas and salivary glands. Therefore, one may suppose that caerulein plus secretin, used in functional exploration of the exocrine pancreas, could exert an influence on acid phosphatase activity (AcP) and its isoenzymes (tartrate sensitive-TsAcP, tartrate resistant-TRAP acid phosphatases) in whole saliva in humans. The current study was conducted in 14 asymptomatic volunteers (six woman and eight men, mean age 34, range 27-45). Salivary secretions were collected under basal conditions (intravenous infusion of 0.15 mol l-1 NaCl) and during intravenous infusion of secretin plus caerulein at different doses. Stimulation with secretin (50 mKE kg-1 min-1) and caerulein (2.5 ng kg-1 min-1) resulted in a marked and rapid decrease of salivary flow rate. TRAP activity decreased during the first 20 min of hormonal infusion (1.09 +/- 0.19 mU ml-1 vs. 1.93 +/- 0.18 mU ml-1, 1.16 +/- 0.12 mU ml-1 vs. 1.86 +/- 0.17 mU ml-1, p < 0.05). AcP and TsAcP activity during intravenous infusion of secretin plus caerulein remained unchanged. These results point to a wider than expected participation of the digestive system in hormonal control of biochemical processes taking place inside the oral cavity.